098
FXUS66 KSGX 191728
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
928 AM PST THU DEC 19 2024
SYNOPSIS
AREAS OF LOW CLOUDS AND FOG ARE EXPECTED WITHIN A FEW MILES OF THE
COAST TONIGHT INTO FRIDAY MORNING. HIGHS TODAY WILL REMAIN ABOVE
AVERAGE, BUT COASTAL AREAS WILL BE A FEW DEGREES COOLER THAN
YESTERDAY. COOLER CONDITIONS WILL SPREAD FURTHER INLAND FRIDAY
THROUGH THE WEEKEND. CONDITIONS WILL GRADUALLY COOL A FEW DEGREES
EACH DAY FRIDAY THROUGH THE WEEKEND. NIGHT AND MORNING LOW CLOUDS
AND FOG ARE EXPECTED OVER THE WEEKEND, GRADUALLY SPREADING
FURTHER INLAND EACH DAY. GUSTY WESTERLY WINDS OVER THE MOUNTAINS
AND LOCALLY INTO THE DESERTS AND A CHANCE OF SHOWERS ARE EXPECTED
TUESDAY. DRY CONDITIONS SHOULD RETURN BY WEDNESDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
AREAS OF DENSE FOG WERE OBSERVED ALONG THE IMMEDIATE COAST THIS
MORNING. AT 9 AM, FOG HAS MOSTLY CLEARED FROM THE BEACHES BUT WAS
STILL OVER THE COASTAL WATERS. THE HREF IS SHOWING 30 TO 40
PERCENT CHANCE OF DENSE FOG MAINLY ALONG THE INTERSTATE 5 CORRIDOR
TONIGHT INTO EARLY FRIDAY MORNING. HIGHEST CHANCES ARE NEAR THE
ORANGE/LA COUNTY LINE AND SOUTHERN SAN DIEGO COUNTY. LOW CLOUDS
AND FOG ARE EXPECTED TO BE PRESENT EACH NIGHT AND MORNING THROUGH
THE WEEKEND. OVER THE NEXT FEW DAYS, HIGH PRESSURE ALOFT WEAKENS
WHICH WILL HELP THE MARINE LAYER DEEPEN ALLOWING COASTAL LOW
CLOUDS AND FOG WILL EXTEND A LITTLE FARTHER INLAND EACH NIGHT AND
MORNING. WITH THE DEEPENING OF THE MARINE LAYER, FOG AND
VISIBILITY ISSUES WILL BECOME LESS OF A PROBLEM ALONG THE COAST
OVER THE WEEKEND.
HIGHS TODAY WILL BE A FEW DEGREES COOLER THAN YESTERDAY ALONG THE
COAST, WITH MINIMAL CHANGES COMPARED TO YESTERDAY FOR INLAND
LOCATIONS. A GRADUAL COOLING TREND IS EXPECTED FOR FRIDAY THROUGH
THE WEEKEND AS AN UPPER LEVEL TROUGH APPROACHES THE PACIFIC
NORTHWEST. THE TROUGH IS NOT EXPECTED TO DIG FAR ENOUGH SOUTH TO
BRING PRECIPITATION TO SOUTHERN CALIFORNIA, BUT PERIODS OF HIGH
CLOUDS CAN BE EXPECTED IN ADDITION TO THE GRADUAL COOLING. WEAK
RIDGING ALOFT WILL MOVE OVER SOUTHERN CALIFORNIA FOR MONDAY,
BRINGING A FEW DEGREES OF WARMING.
FOR TUESDAY A QUICK MOVING TROUGH OF LOW PRESSURE WILL MOVE ACROSS
THE WEST COAST. LATEST GUIDANCE IS INDICATING LIGHT RAIN IS POSSIBLE
FROM THE COAST TO THE MOUNTAINS. ONSHORE WESTERLY WINDS WILL
INCREASE TUESDAY AND PEAK TUESDAY NIGHT, STRONGEST IN THE MOUNTAINS
AND DESERTS. GUIDANCE IS FAIRLY CONSISTENT ON THE TIMING BEING
TUESDAY AFTERNOON AND EVENING FOR BOTH THE WIND AND PRECIPITATION.
SNOW LEVELS ARE EXPECTED TO STAY ABOVE 7000 FT. GUIDANCE FROM THE
NBM HAS A 40 PERCENT CHANCE OF AT LEAST 0.25" OF RAIN IN THE SAN
BERNARDINO COUNTY MOUNTAINS, WITH ONLY 25 PERCENT CHANCE OF AT LEAST
0.25" IN THE RIVERSIDE AND SAN DIEGO COUNTY MOUNTAINS OVER A 24 HOUR
PERIOD ENDING WEDNESDAY MORNING. FOR THE COAST AND VALLEYS, THERE IS
A 25 TO 35 PERCENT CHANCE OF AT LEAST 0.10" OF RAIN ACCUMULATING
OVER A 24 HOUR PERIOD ENDING WEDNESDAY MORNING. THE TROUGH IS
EXPECTED TO QUICKLY EXIT TO THE EAST, LEAVING DRY CONDITIONS IN IT'S
WAKE FOR MUCH OF WEDNESDAY.
AVIATION
191630Z....COASTS/VALLEYS...VFR AND FEW HIGH CLOUDS AT/ABV 20,000FT
MSL THROUGH THE AFTERNOON. LOW CLOUDS LOOK TO FILL BACK IN AND PUSH
ASHORE AROUND 23-01Z FRIDAY, REACHING AROUND 5 MILES INLAND BY 06Z.
BASES LOOK TO BE A TOUCH HIGHER THAN THIS MORNING, LIKELY AROUND 200-
600FT MSL. VIS RESTRICTIONS 0-3SM POSSIBLE IN INLAND VALLEYS,
COASTAL MESAS, AND WHERE CLOUDS INTERSECT HIGHER TERRAIN, WITH 1-5SM
FOR THE IMMEDIATE COASTS. BRIEF PERIODS OF LOWER VIS BELOW 1SM
POSSIBLE FOR KSAN, PRIMARILY AFTER 06Z.
MOUNTAINS/DESERTS
ASIDE FROM HIGH CLOUDS AT OR ABOVE 20,000FT MSL
FILLING IN TODAY, MOSTLY CLEAR CONDITIONS AND UNRESTRICTED VIS
CONTINUES THROUGH EARLY FRIDAY MORNING.
MARINE
AREAS OF DENSE FOG WITH VISIBILITY 1 NM OR LESS WILL PERSIST FOR THE
NEXT FEW HOURS, LIFTING BY 11 AM. DENSE FOG IS POSSIBLE AGAIN THIS
EVENING INTO FRIDAY MORNING, BUT WILL BE PATCHIER AND LIFT BY 10 AM.
LONG PERIOD WEST SWELL LATE SATURDAY WILL GENERATE SEAS OF 8-11 FEET
SUNDAY THROUGH WEDNESDAY, PRIMARILY FOR THE OUTER COASTAL WATERS AND
NEAR SAN CLEMENTE ISLAND.
BEACHES
A SERIES OF 16-17 SECOND PERIOD WEST SWELLS (280-290 DEGREES)
BEGINNING SUNDAY WILL BRING HIGH SURF OF 7 TO 9 FEET WITH LOCALLY
HIGHER SETS PRIMARILY TO SAN DIEGO COUNTY BEACHES WHILE ORANGE
COUNTY BEACHES WILL SEE SURF CLOSER TO 4 TO 7 FEET. SURF WILL
SUBSIDE A BIT ON WEDNESDAY, BUT REINFORCING LONG PERIOD SWELLS MAY
MAINTAIN ELEVATED/HIGH SURF FOR MUCH OF NEXT WEEK. HIGH RISK OF
STRONG RIP CURRENTS AND DANGEROUS SWIMMING CONDITIONS, WITH
ADDITIONAL COASTAL IMPACTS POSSIBLE.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...CO
AVIATION/MARINE/BEACHES...ZUBER/WESTERINK
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